1. Field of the Invention
This invention relates to circulating nipples used for filling well casing and for circulating fluid through well casing while setting or running the casing in a well, and more particularly, to a circulating nipple having an extended neck portion adapted for receiving a pipe wrench thereon and having holes therein adapted for receiving a handle or operating bar therethrough to facilitate installation and removal of the nipple.
2. Description of the Prior Art
It is conventional practice to drill a well to a desired depth and set casing in the well by running a casing string and then cementing the casing in place. The casing string is made up by connecting a plurality of casing sections or joints as the string is lowered into the well. The casing string is held stationary while each section of the casing is connected to the top of the existing casing string. The casing string is then lowered until the top of the string approaches the level of the rig floor. The next section of casing is assembled on the casing string, and the casing is again lowered. As each length of casing or casing section is connected, a circulating nipple, sometimes referred to as a circulating swage, is made up on the upper end of the casing string. The nipple is designed with a casing or tubing pin thread at the bottom and a smaller connection at the top for engagement with fluid flow lines. This top connection is typically a two-inch FIG. 1502 female connection.
Since the sections of the pipe forming the casing are relatively long, the top of the casing may be as high as thirty to forty feet above the rig floor which requires that the nipple be made up on the upper section of casing that far above the rig floor. This necessitates that the nipple be made up on the casing by hand and tightened with the use of hand-held chain tongs. Prior art circulating nipples are relatively long and heavy, and the outer surface of the nipple is usually a smooth, machined finish. This finish makes it difficult for the chain tongs to "bite" into the surface. As a result, the chain tongs frequently slip which can cause loss of balance of the person trying to make up the nipple as well as increasing the time required to complete the task. In addition, the weight and length of the nipple adds to the problem of maneuvering it into position on the casing.
Therefore, there is a need for a circulating nipple which is easier to handle and position on the casing string and which is also more easily made up on the casing string. The present invention addresses this need in several ways. Because the nipple is designed so that it does not need to be made up with chain tongs, the length and weight of the nipple are approximately thirty to thirty-five percent less than prior art nipples. The lighter weight and shorter length combine to make the nipple easier to handle, especially when making up the casing string a large distance above the rig floor. A neck portion of the nipple has been lengthened compared to the prior art, allowing the use of a pipe wrench thereon if desired to make the nipple up in the casing. Further, holes have been provided on the circulating nipple which allow the use of a handle or operating bar to tighten the nipple. The operating bar is the same as, or similar to, the type used to open and close plug valves, such as Halliburton Lo-Torc.RTM. plug valves. Because the bar is inserted into a hole, there is extremely little chance that the bar will slip, thereby minimizing the dangers that are present with the use of chain tongs on prior art nipples. Thus, the circulating nipple of the present invention may be made up more quickly and in a manner which is relatively safer for the person making up the nipple and other personnel on the rig floor.